KR20020076377A - Inside conductive material for cathode ray tube - Google Patents

Abstract

PURPOSE: A conductive material is provided to achieve improved adhesive force of conductive film formed at the inner surface of a funnel of a CRT, while shortening evacuation time and improving life span of a CRT. CONSTITUTION: A conductive material for interior of a CRT, contains graphite particles and a water dispersion medium containing potassium silicates and dispersion agent. The potassium silicate of the water dispersion medium consists of SiO2 and K2O having a mole ratio of 4.5 to 6. The potassium silicate is obtained by adding a hydro silica gel to the potassium silicate solution where SiO2 and K2O have a mole ratio of 4.5 or lower. The graphite particle is 20 to 80 weight parts, calculated in terms of a sold 100 weight parts of the conductive material, the potassium silicate is 20 to 80 weight parts, and the dispersion agent is 1 to 3 weight parts.

Description

Inside conductive material for cathode ray tube

The present invention relates to a conductive material for embedding a cathode ray tube, and more particularly, a conductive material for embedding a cathode ray tube, which is used to form a conductive film formed on an inner surface of a funnel constituting a cathode ray tube and can improve adhesion of the conductive film. It is about.

The cathode ray tube is formed with a conductive film made of a conductive material on the inner and outer surfaces of the funnel so as to act as a capacitor. This conductive film has a function of accelerating an electron beam by applying a high voltage, and collecting secondary electrons generated from a shadow mask, a magnetic shield material, a fluorescent surface, and the like.

The conductive material constituting the conductive film is composed of graphite, an adhesive, and a dispersant, and may further add a metal oxide to increase electrical resistance. Looking at the conductive film and the method for producing a cathode ray tube employing the same using such a conductive material as follows.

The conductive material is coated on the inner or outer surface of the funnel portion using a spray method, a deposition method, a brush, a sponge, or the like, and a conductive film is formed by drying and heating in air. Thus, the funnel part in which the conductive film was formed and the panel in which the fluorescent film was formed on the inner side were sealed at a temperature of about 450 ° C. using a low melting point glass, and an electron gun for generating an electron beam was mounted on the neck of the funnel. The cathode ray tube is completed by heating and exhausting.

Since the conductive film formed on the inner surface of the funnel of the cathode ray tube adsorbs moisture and various gases in the atmosphere, the adsorption gas is removed from the conductive film by heating the tube immediately before the sealing process of the cathode ray tube and reducing the exhaust gas. However, even if such exhaust treatment is performed, some of the adsorbed gas adsorbed on the conductive film is gradually released during the operation of the cathode ray tube, and this gas may cause an undesirable reaction with the cathode of the tube, thereby degrading the function of the cathode.

On the other hand, during the manufacturing process of the cathode ray tube, if the conductive film forming material is partially peeled off from the inner surface of the funnel, there is a problem that arc discharge or electrical leakage of the electron gun occurs during operation of the cathode ray tube. Since such arc discharge or electrical leakage impairs the high voltage stability of the tube, it is necessary to strongly adhere the conductive film to the inner surface of the funnel so that the conductive film does not peel off even when subjected to vibration or shock.

JP 55-2042, JP 3-59542, and JP 63-45428 are metal oxide particles added to a conductive material, such as Fe, Ti, Co, Ni, Cr, Mn, Al, and Si. The selected metal oxide is used. In addition, Japanese Patent Application No. 63-45428 attaches metal oxide particles such as negatively charged graphite particles and positively charged TiO _{2 in} order to disperse the negatively charged and positively charged particles in a stable state in a negatively charged dispersion medium. It is known to disperse in the form of composite particles to which negatively charged SiO ₂ particles are attached.

In addition, Japanese Unexamined Patent Publication No. 61-20990 discloses a method for adding silicon carbide particles in addition to graphite particles in order to improve the adhesion of the conductive film formed on the inner surface of the funnel, and US Pat. No. 4,479,824 adds a silicon monomer in addition to the graphite particles. The method of suppressing peeling of an electrically conductive film is disclosed.

On the other hand, according to Japanese Patent Application Laid-Open No. 52-52362 and Japanese Patent Application Laid-Open No. 63-45428, a method of using lithium silicate, potassium silicate or sodium silicate as an adhesive when forming a conductive film is known. In Japanese Patent Laid-Open No. 3-141539, a method of using cement having less adsorption to moisture or gas as an adhesive when forming a conductive film is described, and Japanese Patent Laid-Open No. 63-114025 has a metal hydride having a gas adsorption release function. A method of adding is disclosed.

In addition, Japanese Patent Application Laid-Open No. 6-093079 discloses a method of using potassium silicate having low water adsorption to gas as an adhesive.

However, the conductive film produced by the above-described methods still has a room for improvement because the adhesion to the inner surface of the funnel does not reach a satisfactory level. In addition, since the time required for the heat degassing process for releasing the adsorbed moisture, carbon dioxide gas, etc., when left in the air after firing the conductive film, there is a problem of lowering the productivity of the cathode ray tube.

The technical problem to be achieved by the present invention is to solve the above problems, not only significantly improve the adhesion to the inner surface of the funnel, but also shorten the time required for the heat degassing process to improve the cathode ray tube built-in conductive wire conductive To provide the material.

Another technical problem to be solved by the present invention is to provide a cathode ray tube having improved performance such as lifetime by employing a conductive film formed from the conductive material.

In order to achieve the above technical problem, in the present invention, in the conductive material for interior of the cathode ray tube containing a water dispersion and graphite particles containing potassium silicate and a dispersant,

The molar ratio of silicon dioxide (SiO ₂ ) and potassium oxide (K ₂ O) constituting potassium silicate in the aqueous dispersion in the aqueous dispersion is in the range of 4.5 to 6, and potassium silicate having such molar ratio characteristics is silicon dioxide (SiO Provided is a conductive material for a cathode ray tube embedded, characterized in that obtained by adding hydro silica gel to an aqueous potassium silicate solution having a molar ratio of ₂ ) and potassium oxide (K ₂ O) is less than 4.5.

In the conductive material of the present invention, the content of the graphite particles is 20 to 80 parts by weight based on 100 parts by weight of the solid content of the conductive material, the content of potassium silicate is 20 to 80 parts by weight, the content of the dispersant is 1 to 3 It is preferable that it is a weight part.

The conductive material for interior of the cathode ray tube of the present invention may further contain a metal compound. As the metal compound, at least one selected from the group consisting of iron oxide (Fe ₂ O ₃ ), titanium dioxide (TiO ₂ ), and silicon carbide (SiC) is used. And in the conductive material having such a composition, the content of the graphite particles is 15 to 50 parts by weight, the content of potassium silicate is 20 to 50 parts by weight based on 100 parts by weight of solid content of the conductive material, the content of the metal compound is 10 to It is 50 weight part, and it is preferable that the content of a dispersing agent is 1-3 weight part.

Another technical problem of the present invention is achieved by a cathode ray tube employing a conductive film formed from a conductive material. At this time, the conductive film is particularly formed on the inner surface of the funnel.

The conductive material for incorporating cathode ray tubes of the present invention uses potassium silicate having a molar ratio of silicon dioxide (SiO ₂ ) and potassium oxide (K ₂ O) of 4.5 to 6 as an adhesive, and such potassium silicate is silicon dioxide ( It is obtained by adding soluble hydro silica gel to water in an aqueous potassium silicate solution having a molar ratio of SiO ₂ ) to potassium oxide (K ₂ O) of less than 4.5. If the molar ratio of silicon dioxide and potassium oxide in potassium silicate exceeds 6, the conductive material gels and the adhesive strength of the conductive film formed from the conductive material is poor, and silicon dioxide (SiO ₂ ) and potassium oxide (K ₂ O). If the molar ratio is less than 4.5, there is a problem of adsorbing a lot of moisture and gas.

As an aqueous potassium silicate solution having a molar ratio of silicon dioxide (SiO ₂ ) to potassium oxide (K ₂ O) of less than 4.5, it may be obtained under the trade name KASIL (PQ) or trade name Okasir (Tokyo Cargo Chemical Co., Ltd.). It is available from PM (PQ Corporation) or a brand name DARACLAR (Grace Co., Ltd.).

The electrically-conductive material of this invention is comprised from the graphite particle and the water dispersion medium containing potassium silicate and a dispersing agent. Here, the molar ratio of silicon dioxide (SiO ₂ ) and potassium oxide (K ₂ O) in the aqueous dispersion is 4.5 to 6, and potassium silicate having such characteristics is particularly characterized in that of silicon dioxide (SiO ₂ ) and potassium oxide (K ₂ O). It is particularly preferable in terms of the adhesive strength of the conductive film to use one obtained by adding hydro silica gel to an aqueous potassium silicate solution having a molar ratio of less than 4.5.

Hydrosilica gel is different from the colloidal silica, as shown in Table 1, such as properties, water solubility, particle size, and the like, in particular, the molar ratio of silicon dioxide and potassium oxide at the time of gelation when the adhesive is prepared.

That is, hydrosilica gel has a property of gelling when the molar ratio of silicon dioxide and potassium oxide exceeds 6, and colloidal silica has a property of gelling when the molar ratio of silicon dioxide and potassium oxide exceeds 5. Therefore, when potassium silicate having a molar ratio of silicon dioxide and potassium oxide of more than 5 is manufactured using colloidal silica, the conductive material containing it as an adhesive gels and the adhesive strength of the conductive film formed therefrom becomes poor. Problems arise. In addition, even when using colloidal silica and producing potassium silicate having a molar ratio of silicon dioxide and potassium oxide of 4.5 to 5, the moisture and gas adsorption amount of the conductive film does not reach a desired level, which is not preferable.

In the conductive material, it is preferable to use graphite particles having a particle diameter of 0.5 to 20 µm in terms of the conductivity of the conductive film, and the content thereof is preferably 20 to 80 parts by weight based on 100 parts by weight of the solid content of the conductive material, particularly 30 to It is more preferable that it is 70 weight part. If the content of the graphite particles is less than 20 parts by weight, the conductive properties of the conductive film is lowered, if more than 80 parts by weight, there is a problem that the adhesive strength of the conductive film is lowered. The potassium silicate is preferably 20 to 80 parts by weight based on 100 parts by weight of the solid content of the conductive material, and particularly preferably 30 to 40 parts by weight. If the content of potassium silicate is more than 80 parts by weight, the content of the graphite particles is relatively reduced and the conductivity of the conductive film is lowered). If the content is less than 20 parts by weight, the adhesion of the conductive film is not good, which is not preferable.

The dispersant contained in the aqueous dispersion is not particularly limited, but carboxycellulose is used in the present invention. The content of this dispersant is 1 to 3 parts by weight, and particularly preferably 2 parts by weight based on 100 parts by weight of the conductive material solid content. If the content of the dispersant is less than 1 part by weight, the dispersibility of each component in the conductive material is poor, and if the content of the dispersant is more than 3 parts by weight, the content of graphite particles and potassium silicate as an adhesive is relatively decreased, which is not preferable.

In addition, the conductive material of the present invention may further contain a metal compound in addition to the aqueous dispersion containing graphite particles, potassium silicate and a dispersant. In this way, when the metal compound is added, an effect of slightly increasing the electrical resistance value can be obtained. Here, as the metal compound, at least one selected from the group consisting of iron oxide (Fe ₂ O ₃ ), titanium dioxide (TiO ₂ ), and silicon carbide (SiC) is used, and the content thereof is based on 100 parts by weight of the conductive material solids from 5 to 5 parts. It is preferable that it is 50 weight part, and it is more preferable that it is 10-40 weight part especially. If the content of the metal compound is less than 5 parts by weight, there is no effect of resistance control, and if it exceeds 50 parts by weight, the resistance is too high, which is not preferable.

In the case of constituting the conductive material using a metal compound, the content of the graphite particles is 15 to 50 parts by weight, preferably 30 to 40 parts by weight based on 100 parts by weight of the solid of the conductive material. The content of potassium silicate is 20 to 50 parts by weight, preferably 30 to 40 parts by weight, and the content of the dispersant is 1 to 3 parts by weight based on 100 parts by weight of the conductive material solids, Preferably it is about 2 parts by weight.

Looking at the method for forming a conductive film on the inner surface of the cathode ray tube funnel using the conductive material having the above-described composition is as follows.

First, an aqueous potassium silicate solution having a molar ratio of silicon dioxide and potassium oxide of 4.5 to 6 is prepared. In the present invention, an aqueous potassium silicate solution having such molar ratio characteristics is particularly prepared by adding hydro silica gel to an aqueous potassium silicate solution having a molar ratio of silicon dioxide (SiO ₂ ) to potassium oxide (K ₂ O) of less than 4.5.

Graphite particles, pure water, and a dispersant are added to an aqueous potassium silicate solution having a molar ratio of silicon dioxide (SiO ₂ ) and potassium oxide (K ₂ O) of 4.5 to 6, and then sufficiently mixed to prepare a conductive material. In the case of manufacturing the conductive material, at least one metal compound selected from the group consisting of iron oxide (Fe ₂ O ₃ ), titanium dioxide (TiO ₂ ) and silicon carbide (SiC) may be further added.

Coating the conductive material prepared according to the above method on the inner surface of the cathode ray tube funnel, and then dried and calcined at 400 to 470 ° C, preferably 440 to 450 ° C to provide a cathode ray tube employing the conductive film formed on the inner surface of the funnel. Complete

Hereinafter, the present invention will be described in detail with reference to the following examples, but the present invention is not limited to the following examples.

<Example 1>

500 g of potassium silicate aqueous solution (solid content 30.0%) of molar ratio 3.5 was put into 1 liter beaker, and the high speed stirrer was equipped with the heating heater. The heating temperature of the beaker was 70 ° C., while slowly stirring the whole amount of 161.4 g of hydro silica gel (solid content 33%) while stirring at high speed at 3000 rpm, the stirring was continued until it became transparent, and then 151.648 g of pure water was naturally cooled. Was added slowly to obtain an aqueous potassium silicate solution (solid content 25%) with a molar ratio of 5.3.

Then, to 439 ml of pure water, 360 g of an aqueous potassium silicate solution having a molar ratio 5.3 prepared according to the above procedure, 195 g of graphite particles having an average particle diameter of about 2 μm, and 6 g of carboxycellulose (CMC) were added, and the mixture was sufficiently stirred in a ball mill to conduct conductivity. The material was prepared. The conductive material thus obtained was coated on the inner surface of the cathode ray tube funnel, and then dried and calcined at 450 ° C. for 1 hour to form a conductive film on the inner surface of the cathode ray funnel.

<Example 2>

For 500 g of potassium silicate aqueous solution with a molar ratio of 3.5, 89.66 g of hydrosilica gel and 128.66 g of pure water were used in the same manner as in Example 1 to prepare an aqueous potassium silicate solution with a molar ratio of 4.5 (solid content of 25%). Using this, a conductive film was formed on the inner surface of the cathode ray tube funnel.

<Example 3>

When preparing the conductive material, the molar ratio was carried out in the same manner as in Example 1 except that the graphite particles having a pure water content of 430 ml, an average particle diameter of about 2 μm, and 105 g of Fe ₂ O ₃ were further added. An aqueous solution of potassium silicate (solid content: 25%) of 5.3 was prepared, and a conductive film was formed on the inner surface of the cathode ray tube funnel.

<Example 4>

In preparing the conductive material, an aqueous potassium silicate solution (solid content: 25%) having a molar ratio of 5.3 was prepared by following the same method as Example 3, except that TiO ₂ was used instead of Fe ₂ O ₃ . A conductive film was formed on the inner surface of the funnel.

Example 5

In preparing the conductive material, an aqueous potassium silicate solution (solid content: 25%) having a molar ratio of 5.3 was prepared by following the same method as Example 3, except that SiC was used instead of TiO ₂ , and was used on the inner surface of the cathode ray tube funnel. A conductive film was formed.

Comparative Example 1

500 g of an aqueous molar ratio 3.5 potassium silicate solution (solid content 30%) was put into a 1 liter beaker, and the high speed stirrer was equipped with the heating heater. The heating temperature of the beaker was 40 ° C, while slowly stirring the entire amount of 145 g of colloidal silica (solid content of 20.5%) while stirring at high speed at 120 rpm, and stirring was continued for about 60 minutes until it became clear, and then the aqueous potassium silicate solution having a molar ratio of 4.5 (Solid content 27.9%) was obtained.

Then, to 476 ml of pure water, 323 g of an aqueous potassium silicate solution having a molar ratio of 4.5 prepared according to the above procedure, 195 g of graphite particles having an average particle diameter of about 2 μm, and 6 g of carboxycellulose (CMC) were added, and the mixture was sufficiently stirred in a ball mill for conduction. The material was prepared. The conductive material thus obtained was coated on the inner surface of the cathode ray tube funnel, and then dried and calcined at 450 ° C. for 1 hour to form a conductive film on the inner surface of the cathode ray funnel.

Comparative Example 2

An aqueous potassium silicate solution (solid content 25%) having a molar ratio of 6.6 was prepared according to the same procedure as in Example 1 except that 277.93 g of hydro silica gel and 188.91 g of pure water were used with respect to 500 g of potassium silicate solution having a molar ratio of 3.5. Using this, a conductive film was formed on the inner surface of the cathode ray tube funnel.

Evaluation of the characteristics of the conductive film prepared according to Examples 1 to 5 and Comparative Examples 1 to 2 was carried out according to the following method, and the evaluation results are shown in Table 2 below.

(1) resistivity

A method effective for evaluating a low resistance sample commonly referred to as a four-stage needle method is employed, and a 3540 millimeter groove high tester (trade name, manufactured by HIOKI Co., Ltd.) is used as the resistance measurement instrument.

(2) adhesive

The adhesiveness of the conductive film is adhered and peeled off the surface thereof, and the peeling state of the conductive film is observed and evaluated. The tape peeling test is conducted according to ASTM D 3359.

division Resistivity value [Ωcm] Adhesive Example 1 0.04 100/100 Example 2 0.04 100/100 Example 3 0.37 100/100 Example 4 0.39 100/100 Example 5 0.43 100/100 Comparative Example 1 0.04 8/100 Comparative Example 2 0.04 5/100

From Table 2, it can be seen that the conductive films produced according to Examples 1 to 5 exhibited a specific value with a specific resistance, and the adhesiveness was remarkably improved as compared with the case of Comparative Examples 1 to 2. Here, the resistivity characteristics of the conductive films of Comparative Examples 1 and 2 showed almost the same results as those of Examples 1 to 5.

On the other hand, in the cathode ray tube employing the conductive film prepared according to Examples 1 to 5 and Comparative Examples 1 to 2, the heat exhaust temperature and the time spent in the heat exhaust process were compared.

As a result of analysis, the cathode ray tubes according to Examples 1 to 5 were able to shorten the time required for the heat exhaust process compared with the case of Comparative Examples 1 to 2, and it was possible to lower the exhaust heating temperature. In addition, the cathode ray tubes according to Examples 1 to 5 can be exhausted to a high vibration degree under the same process conditions as in the conventional case, thereby improving the attained vacuum degree, as well as excellent adhesion of the conductive film to the inner surface of the funnel. Could increase its lifespan.

When the conductive film is formed in the cathode ray tube funnel according to the present invention, the adhesion of the conductive film is remarkably improved by using potassium silicate having a molar ratio of silicon dioxide (SiO ₂ ) and potassium oxide (K ₂ O) of 4.5 to 6 in the aqueous dispersion as an adhesive. Can be improved. In addition, when potassium silicate is used as the adhesive, the amount of gas discharged in vacuum heating exhaust is reduced, so that the exhaust time can be shortened, and even if the exhaust heating temperature is adjusted low, the quality almost equivalent to the conventional one can be maintained, and the vibration The phenomenon that the conductive material is peeled off by an external force such as an impact or the like can be effectively suppressed. As a result, the life characteristics of the cathode ray tube can be improved, and the productivity of the cathode ray tube can be improved.

Although the present invention has been described with reference to the above embodiments, it is merely illustrative, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. . Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (8)

In the conductive material for interior of a cathode ray tube containing an aqueous dispersion containing potassium silicate and a dispersant and graphite particles, The molar ratio of silicon dioxide (SiO ₂ ) and potassium oxide (K ₂ O) constituting potassium silicate in the aqueous dispersion is in the range of 4.5 to 6, Potassium silicate having such molar ratio characteristics A conductive material for incorporating a cathode ray tube, characterized in that obtained by adding hydro silica gel to an aqueous potassium silicate solution having a molar ratio of silicon dioxide (SiO ₂ ) to potassium oxide (K ₂ O) of less than 4.5. According to claim 1, wherein the graphite particles are 20 to 80 parts by weight based on 100 parts by weight of the solid content of the conductive material, the content of potassium silicate is 20 to 80 parts by weight, the content of the dispersant is 1 to 3 parts by weight Cathode ray tube conductive material, characterized in that. The conductive material for embedding a cathode ray tube according to claim 1, further comprising a metal compound. 4. The conductive material for interior of a cathode ray tube according to claim 3, wherein the metal compound is at least one selected from the group consisting of iron oxide (Fe ₂ O ₃ ), titanium dioxide (TiO ₂ ) and silicon carbide (SiC). According to claim 3, wherein the graphite particles are 15 to 50 parts by weight based on 100 parts by weight of the solid content of the conductive material, 20 to 50 parts by weight of potassium silicate, 5 to 50 parts by weight of the metal compound And the content of the dispersant is 1 to 3 parts by weight, the conductive material for a cathode ray tube embedded. The conductive material for a cathode ray tube interior according to claim 1, wherein the dispersant is carboxycellulose. The cathode ray tube which employ | adopts the electrically conductive film formed from the electrically-conductive material in any one of Claims 1-6. The cathode ray tube according to claim 7, wherein the conductive film is formed on an inner surface of the funnel.